Audio and video conferences between more than two participants are becoming more important today as they are increasingly more common.
In this sense, it is very common in the state of the art to add a type of server to assist either with the organization and synchronization of the parties involved or with the mixing of the media streams, media being understood as the data associated with the exchange of audio and video signals between the participating terminals.
The use of a single server handling the conference between terminals by means of a star configuration is known in the state of the art.
Multiple distributed servers cooperating with one another are used in other cases such that it is necessary for servers to handle part of the synchronization and the characteristics of mixing media supporting the conference, like in the case of using a single server.
In any of the cases in which one or more servers is used, there are cases in which the participating terminals are well communicated with one another by means of a low-congestion network, but it may not be capable of accessing an external conference server. Even if the external conference server can be accessed, the connectivity with same may not be good enough, and in any case worse than that existing between them, especially if the participating terminals are arranged on a local area network.
Therefore the centralized proposal where a server takes care of the functionalities of synchronizing or mixing the media streams is not always the best method. The same occurs for the case in which several conference servers cooperate and control the exchange and/or information of the media.
The multipoint conference without using a server is possible, as described for example in patent document U.S. 2007/0005804A1, which teaches several ways to take advantage of transmitting to multiple destinations in a multipoint conference without server, in which when a user decides to set up an audio/video conference with a group of users, he/she sends a petition to all the terminals, such that the users have the option to accept or reject it. When they accept the petition, they join the conference in which the media stream is distributed by multicast technologies, unlike the present invention in which transmission to multiple destinations (multicast) is not used to distribute the media streams but rather they are distributed to a single destination, as will be described below.
In this case the mentioned proposal without server represents a solution that is not easily applicable to a telephony network because it is based on client-to-client protocols. In this case it is necessary to reuse existing protocols provided it is possible. Networks of this kind further set up communications based on sessions consisting of streams, such that the client-to-client proposal is not directly applicable thereto. A new solution that is based on the same concept of multimedia sessions supported by telephony networks is therefore needed.
Patent document EP 1696630 describing a solution for a serverless multipoint conference between communication nodes by means of a client-to-client network should also be mentioned. The media frames are shared between terminals according to their processing capacities to mix and distribute them.
In this case the serverless multi-party, real-time audio communication uses a client-to-client protocol which does not present interoperability with standardized systems or communication systems capable of functioning in an IMS (IP Multimedia Subsystem) network in which the communication is client-to-client, such that it cannot be integrated with standardized telephony systems without important actions or extensions. This determines a serious limitation, taking into account the increase in telephony solutions arising today.